The effect of genotype and planting density on the growth patterns and selection of local varieties of Sugi (Cryptomeria japonica)

We analyzed the effect of genotype and planting density on the growth patterns of height and diameter at breast height (DBH) and the efficiency of indirect early selection targeting on the low planting density using stem analysis data obtained from a test site composed of 6 cultivars and 3 planting densities (5, 000, 3, 000, 1, 500 trees/ha) at stand age 28. The growth pattern of height was mainly affected by genotype, but the effect of planting density was small. The growth pattern of DBH was affected by both genotype and planting density. Our results showed the importance of selection of the genotype of seedlings for the control of growth in plantations of Sugi. The results of genetic evaluation obtained at general planting density (3, 000 trees/ha) could be applied for the prediction of genetic performance of growth traits at different planting densities. Approximately 15 years would be required to obtain 80% of genetic gain at stand age 28 with the plantation of 1, 500 trees/ha according to the test results obtained at the plantation of general planting density (3, 000 trees/ha).